Fig. 3

Schematic illustration of generic biosynthetic pathways of PMLA in microorganisms. Using glucose as carbon source, it is converted into phosphoenolpyruvate and pyruvate by glycolysis, both finally producing malate in the cytoplasm via the reductive pathway. In parallel, pyruvate is transported into the mitochondria, is oxidized and decarboxylated to form acetyl-CoA, and then joins the TCA cycle. After acetyl-CoA condenses with oxaloacetate to form citric acid, it undergoes a series of enzymatic reactions to produce malate via the oxidative pathway. Alternatively, a shortcut, the glyoxylate shunt, utilizing glyoxylate as an intermediate can bypass the TCA cycle to produce malates. Malates produced inside mitochondria are transported to the cytoplasm through a dicarboxylate transporter, where PMLA synthetase finally polymerizes them into PMLA